Skip-stitch mechanism for household zigzag sewing machines



March 18, 1969 z. l.. sAGl 3,433,190

SKIP-STITCH MECHANISM FOR HOUSEHOLD ZIGZAG SEWINO MACHINES Filed March v, 1967 sheet of 2 INVENTOR. Zslgmond L. Sagl Shea?l of 2 Z. L. SAGI v INVENTOR. Zsgm'ond L. Sagl March 18, 1969 SKIP-STITCH MECHANISM FOR HOUSEHOLD ZIGZAG SEWING MACHINES Filed March 7, 1967 United States Patent O 18 Claims ABSTRACT OF THE DISCLOSURE A zigzag sewing machine equipped with cam actuated skip-stitch mechanism which provides for skipped stitches by interrupting the endwise reciprocation of the needle-bar at predetermined intervals dependent upon the contour of the cam or cams that actuate the mechamsm.

Backgronnd of the invention In some of the prior art skip stitching mechanisms the normal thread concatenation was prevented by utilizing various methods such as manipulation of the looper or needle thread or by providing special needles or attachments in the bed of the sewing machine. In all of these methods the needle penetrated the work material during the skipping of the stitches which resulted in undesirable needle holes in all work material and prohibited use with some work fabrics in which such holes could not be tolerated. In addition, the mechanisms utilized were either not sufficiently reliable for modern, sophisticated household sewing machines, occupied too much space or were inconvenient in that needles or attachments had to be changed each time skip stitches were required.

In other prior art mechanisms the reciprocation of a needle bar was interrupted to prevent formation of stitches. In one such type of mechanism, one of two needle-bars mounted in the machine was manually disconnected to aid the operator in the production of angular seams. The United States Patent No. 2,346,467, Apr. 11, 1944, Bills et al., `discloses another needle-bar interrupting mechanism, which, however, is built into an industrial type tufting machine that does not have zigzag stitching capability. The combination of needle jogging motion with correlated needle bar interruption does not exist in the Bills et al. tufting machine. The Bills et al. needle-bar interrupting mechanism serves only for controlling the location of tuft formation and is continuously under the control of a permanently mounted cam, which mechanism cannot, therefore, readily be called into and out of action. Since the Bills et al. tufting machine is constructed so that reciprocation of the needle-bar is continuously under the control of the permanently mounted cam it can be utilized for only one type of stitching operf ation. In addition the Bills et al. skip-stitch mechanism is bulky and occupies a large amount of space relative to the size of the machine.

Summary of the invention The present invention comprises needle-bar interrupting mechanism mounted in a zigzag sewing machine and responsive to a cam mounted on the same cam shaft that supports and rotates the cams that actuate the zigzag mechanism. The needle-bar interrupting mechanism serves to interrupt the endwise reciprocation of the needlebar at predetermined intervals, dependent upon the contour of the cam, simultaneously with the operation ot' the zigzag mechanism. The cam to which the needle-bar interrupting mechanism responds may be removable to provide a virtually unlimited selection of skip-stitch patterns. The present invention also provides mechanism effective during the ordinary skip-stitch mode of the sewing machine for rendering the interrupting mechanism non-responsive to the cam.

The present invention avoids the drawbacks of the prior art skip-stitch mechanisms briefly outlined above by placing the relatively small and compact skip-stitch mechanism in an unused area of the sewing machine, and by utilizing some of the existing zigzag mechanism. The skip-stitch mechanism of the present invention is reliable and does not require an exchange of needles or attachments when skip-stitches are desired, and of course since the skip-stitches are produced by interrupting the reciprocation of the needle-bar no undesirable perforations are made in the work material `during the skip-stitch mode of operation.

It is an object of this invention to provide an improved skip-stitch mechanism for a zigzag sewing machine.

It is another object of this invention to provide for an improved mechanism for interrupting the vertical reciprocation of the sewing machine at predetermined intervals.

It is still another object of this invention to provide for a skip-stitch mechanism that is actuated by the lateral zigzag motion of the sewing machine needle-bar.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in the art to understand the functions, operation, construction and advantages of it when read in conjunction with the accompanying drawings in which:

Brie)c description of the drawings FIG. 1 is a perspective view of the skip-stitch mechanism of the present invention.

FIG. 2 is an enlarged sectional view taken substantially along lines 2-2 of FIG. 1 and showing the needle-bar driving stud disengaged from the needle-bar.

FIG. 3 is the same view as that of FIG. 2 but it shows the needle-bar driving stud locked to the needle-bar.

FIG. 4 is an exploded perspective View of elements of the present invention that releasably lock the driving stud to the needle-bar.

FIG. 5 is a top plan view of a sewing machine housing the skip-stitch mechanism of the present invention.

Description of the preferred embodiment The present invention is illustrated in the drawings as embodied in a sewing machine having a zigzag mechanism that is herein illustrated and described only insofar as it is believed to be necessary for an understanding of this invention. Reference may be had to the United States Patents No. 3,191,559, lune 29, 1965, Marsh et al., a-nd No. 2,862,468, Dec. 2, 1958, R. E. Johnson, for a more complete understanding of such zigzag mechanisms.

With reference to the drawings, there is illustrated a sewing machine 10 having a frame 12 including a bracket arm 14, a head 16 overhanging a bed 18, and a panel 19 in the front face of the bracket arm. Mounted in the head 16 for endwise reciprocation and for vibration laterally of the line of stitch formation, or in other words, for zigzag movements, is a needle-bar 20 adapted to support a needle 21. Lateral vibration is imparted to the needle-bar 20 by a bracket 22 pivotally mounted at one end on a stud 24 and pivotally mounted at the other end on the needle-bar 20. The bracket is connectedto one end of an endwise movable pitman 26, whereby upon actuation of the pitman, lateral vibration is imparted to the needle-bar. The opposite end of the pitman 26 carries a plate 28 pivotally mounted thereon by a pivot pin 30.

The -plate 2:8 and thus the pitman `26 and the needlebar mechanism are biased toward the right, as seen in FIG. 5, by a bias element or spring 32 connected at one end to the pitiman 26 at a point adjacent to its connection with the bracket 22 and anchored at the other end to a bolt 34. There is also provided a spring 36 connected at one end to a plate `37 and at its other end to an arm 38 pivotally mounted in the frame 12 on a stud 40, the free end of which arm 38 abuts the plate 28 to resist overthrow thereof. The plate 28 is thus 'biased against a pair of cam followers 42 and 44 Iwhich are in turn biased into tracking engagement with any selected ones of the cams in a cam stack -46 to provide for actuation of the pitman 26. The cam stack Y46 is mounted for rotation on a vertical post 48 and rotation is imparted thereto by a worm Wheel 50 on the stack that cooperates with a Worm 52 on a rotary arm shaft '54 which is journaled longitudinally of the bracket arm 14.

The pitman 26 is adapted to be shifted to place the pivot pin 30 alternatively substantially over the points of contact between the plate 28 and the cam followers 42 and 44 or at points between these two positions, thereby adjusting the amount of the cam-induced motion of the cam followers 42 and 44 that is transmitted to the plate 28 and thus to the pitman 26 and the needle-bar mechanism. The means for shifting the pitman 26 comprises a lever 56 having a handle section 58 extending through a slot in the panel 19 to be accessible to the operator.

The cai-m followers 42 and `44, respectively, are pivotally mounted and endwise slidable on vertical posts 60 and 62, respectively, 'which are parallel to the axis of the cam stack 46. The post 60 is provided with a plurality of vertically spaced notches 64, each corresponding to one of the individual cams in the cam stack 46, which notches are adapted to be entered selectively by a `knife-like element 66 that extends through a slot in the hub 68 of the cam follower 42 and into the notch, thus positioning the follower 42 and locking the same endwise of the post 60 with respect to the selected one of the cams. Similarly, the post 62 has a plurality of notches 70 adapted to lbe entered by a knife-like element 72 extending through a slot in the hub 74 of the cam follower 44.

In the normal manner, to effect calm selection with either of the cam followers 42 or 44, the respective knifelike element 66 or 72 is retracted from the notches in the post to free the follower for endwise movement, but without retracting the same from the hub of the follower. Thus, as the element 66 or 72 is moved, the respective follower will be moved with it. At the same time, the carnengaging portion of the follower is shifted laterally, clear of the cams so that it can be moved freely, vertically of the cam stack 46.

The cam selector mechanism for the cam follower 42 comprises a shaft 76 mounted in the frame 12 and adapted for rotatable and endwise movements. Secured to the shaft 76 is a crank arm 78 that carries the knife-like element 66 and which is adapted to abut an arm -80 integral with the cam follower 42. Thus, as the shaft 76 is moved endwise inwardly, the lknife-like element 66 is moved out of the notches and the cam follower 42 is pivoted so that the cam engaging end thereof is clear of all the cams. The shaft 76 can then be turned to move the cam follower 42 vertically of the stack 46 to a position opposite any selected cam. The means for moving and for turning the shaft 76 comprise an actuating arm 182 secured to the shaft 74 and having a handle portion 84 extending through the panel 19 to the exterior of the sewing machine. A coil spring 86 mounted on the shaft 76 is disposed between the frame 12 and the crank arm 76 to force the shaft outwardly 'when it is released, this motion being limited by seating of the knife-like element 66 in the notch 64.

With respect to the cam follower 44 the cam selector mechanism comprises a bracket 88 slidably and rotatably mounted on the shaft 76 and having an actuating arm 90 that extends through the panel 19 and terminates in a handle portion 92. Secured to the bracket 88 is a crank arm 94 having an end section 96 adapted to abut an arm 98 integral with the cam follower 44 and secured to the arm 94 is the lknife-like element 72. Thus, when the bracket 88 is pushed inwardly the knife-like element 72 is withdrawn from one of the notches 64 and the cam engaging end of the follower 44 is moved laterally, clear of the cams in the stack 46. When the bracket `818 is pivoted by manipulating the handle 92, the cam follower 44 is shifted endwise of the post 62. When the handle 92 is released, a leaf spring 100 secured by one end to the frame 12 biases the bracket 88 to its normal position as shown in FIG. 4.

Turning now to the mechanism that provides for the skip stitching function of the present invention a counterweighted driving crank 102 driven by the rotary arm shaft 54 is operatively connected to a needle-bar driving stud 104 by an arm 106. The crank 102 also drives a needle thread take up member 1&17 in the usual manner. The stud 104 includes flanges 108 and an apertured hinge pin which receives an elongated bushing 112 to Iwhich it is secured by a screw 114. The bushing 112 slidingly receives the needle-bar 20 which is formed with a lateral slot 116 in the upper section thereof. On the upper end of the bushing 112 there is secured a horizontal plate 118 horizontally slotted to form two spaced ledges 120 defining a slot 122 that receives a needle-bar locking lever 124, formed with anms and 127, which is normally biased into locking engagement with the needlebar. The lever 124 is pivoted in a horizontal plane on a pin 126 mounted vertically in the plate 118 and is biased inwardly toward the needle-bar 20 by a spring 128 connected at one end to the lever and at its other end to a pin 130 mounted on the horizontal plate 118. Aligned 'with the horizontal plate slot 122 is a slot 132 of corresponding width and formed in the bushing 112 so that the leading edge of the arm 127 of the spring biased lever 124 may pass through both slots and into the needlebar slot 116, as shown more clearly in FIG. 3. With the latch lever 124 biased into engagement with the lateral slot 116 in the needle-bar the needle-bar is locked to the stud 104 through the intermediacy of the lever 124, plate 118 and bushing 112. Thus, when the stud 104 is reciprocated vertically by the needle-bar drive train the needlebar is driven in endwise reciprocation. The needle-bar is prevented from turning, as it is reciprocated, by a bar 131, having a leading edge 133, secured to the top of the horizontal plate 118 and a slatted section -135 that extends the entire length of the needle-bar 20. The =bar 131 is positioned to protrude a sufficient distance over the aperture in the plate 118 (FIG. 4) to allow the leading edge 133 of the bar 131 slidingly to engage the elongated slatted section 1315 thereby to prevent the needle-bar from turning.

To activate the skip-stitch mechanism, i.e., to place it into or out of operation there `is provided adjacent the needle-bar 20 an activating arm 134 pivotally mounted at its lower end section on a screw 136 secured inthe head 16. The upper section of the arm 134 in turn i-s pivotally connected to an end of a horizontal bar 138 guided for endwise movement by a grooved plate 140 secured to the frame of the sewing machine. The bar 138 may be manually moved endwise by a control lever 142 that protrudes Vthrough the panel 19 to lbe easily accessible to the operator. The control lever 142 is pivoted at one end on a pin 144 mounted on the plate 37 and is adapted to be received by either of two slots 146 or 147 formed in the bracket arm 14. Secured to and rising from a point intermediate the control lever ends is a stud 148 received by a slot 150 in the horizontal bar 138. As will -be explained in detail below when the control lever 142 -is positioned in the slot 147 the sewing machine remains in the conventional sewing mode but when it is positioned in the slot 146 the sewing machine is placed in the skip-stitch Imode.

Turning now to the operation of the presently disclosed invention, when the control arm 142 is positioned in the slot 147 the sewing machine operates in the conventional manner sewing zigzag or straight stitches depending upon the setting of the other sewing machine controls. When, however, the control lever 142 is moved into the slot 146 and the other sewing machine controls are adjusted for zigzag sewing operation, skipped stitches result. Thus, when the control lever 142 is pivoted to move it into the slot 146 the horizontal bar 138 is pushed to the left, as viewed from the front of the sewing machine, thereby pivoting the arm 134 ina counterclockwise direction, as viewed from the front of the sewing machine, from its normally vertical position to a position forming an acute angle with the vertical. In the skip-stitch mode, when the top section of the needle-bar 20 is pivoted by the zigzag mechanism in a direction away from the ca m a stitch 152 is formed on the inboard side of the center line of the stitches as is normal in zigzag stitching. However, on the reverse lateral swing of the needle-bar the leading edge of the arm 125 of the locking lever 124 is intercepted by the arm 134 forcing the arm 127 of the lever out of the needle-bar slot 116 thereby disconnecting the stud 104 from the needle-bar. With the needle-bar disconnected the stud is free to reciprocate on the needle-bar which comes to a stop at the upper end of its vertical stroke thereby leaving the needle raised above the work material 154 and preventing the formation of a stitch (FIG. 1) on that lateral throw of the needle-bar. It is here noted that the needle-bar is always disconnected at the top of its vertical stroke because the angle of the arm 134 in the skip-stitch position is designed so that, on the disconnect swing of the needle-bar, although the arm 125 could engage the arm 134 near the lower end of the needle-bar stroke the locking lever 124 is not pivoted sufficiently at that point to move the arm 127 out of the needle-bar slot 116. However, as the needle-bar moves upwardly and the arm 125 slides along the angled arm 134 the locking lever is gradually pivoted outwardly away from the needle-bar until, at some point near the top of the vertical stroke, the arm 127 is moved completely out of the needle-bar slot 116 leaving the stud 104 free to slide along the needle-bar. The needle-bar, meanwhile, is slowed to a stop near the top of its vertical stroke by an apertured friction pad 156 adjustably biased against the needle-bar. The friction pad 156 is slidably mounted at one end on a threaded pin 153 formed with a head 155 and is pivotally mounted at its other end on a presser-bar 157. The pin 153 in turn is slidably mounted on an apertured bracket 159 secured to the head 16 of the sewing machine and supports a coil spring 161 captured between the friction pad and the head of the pin. The coil spring 161 acts to bias the pad against the needle-bar, the bias being adjustable by drawing the pin 153 toward or away from the :bracket 159 by adjusting a lock nut 163 threadely engaged by the pin 153.

It is here noted that although, conceivably, any of the cams on the cam stack 46 could be utilized to produce skip-stitches they would be erratic and not suitable for the uses to which the skip stitching function of the sewing machine would ordinarily be applied. Thus, provision is made for mounting a special skip-stitchcam 158 that may be removed at any time from the cam stack 46 and replaced -by other cams designed primarily by zigzag operation or by differently designed skip-stitch cams. The means for removably mounting the cam 158 on the cam stack 46 may utilize any of a number of known designs for removably mounting cams on cam stacks. The means illustrated in the drawing is -set forth in detail in the United States Patent No. 2,924,120, Feb. 9, 1960, Ralph E. Johnson, and includes a collar 160 integrally formed with and rising from the upper surface of the cam 158. The cam 158 may be removably locked to the vertical post 48 by kutilizing a three pronged support spring 162 secured to the post 48 and a pin 164 received by an elongated hole 166 in the cam 158.

Having thus set forth the nature of this invention, what is claimed herein is:

1. A sewing machine having a frame, work feeding mechanism, a needle-bar carried in said frame for endwise reciprocatory and lateral jogging movements, a needle carried by said needle-bar, actuating means carried on the frame, means driven by said actuating means for imparting endwise reciprocatory movements to said needle-bar, means for interrupting the endwise reciprocation of said needle-bar at predetermined intervals, a cam shaft mounted in said sewing machine frame, means operated by said actuating means for driving said cam shaft, -at least one cam means carried by said cam shaft, means responsive to a cam means carried by said cam shaft for imparting lateral jogging movements to said needle-bar to provide for the production of zigzag stitches by permitting said needle to reciprocate at predetermined intervals on a first side of a center line extending in the direction of work material feed and at other predetermined intervals on a second side of .the center line, means responsive to a cam means carried by said cam shaft for effecting operation of said needle-bar interrupting means simultaneously with the operation of said needle jogging means, and means eective during operation of said actuating means for selectively rendering said needle-bar interrupting means non-responsive to said at least one cam means.

2. A sewing machine as set forth in claim 1 wherein said interrupting means includes means operated by the needle-bar as it jogs to the first side of the center line for interrupting the reciprocation of the needle-bar and for resuming the reciprocation of the needle-bar as the needlebar jogs to the second side of the center line.

3. A sewing machine as set forth in claim 1 wherein said interrupting means and said needle jogging means are both actuated by a single cam means.

4. A sewing machine as set forth in claim 1 wherein said interrupting means includes a movable activating arm and said means for selectively rendering said interrupting means non-responsive includes operator influenced means, said last named means including a lever protruding from the contines of the sewing machine frame, said lever being operatively connected to said movable activating arm.

5. A sewing machine as set forth in claim 4 wherein said actu-ating means includes a rotary arm shaft and said means for imparting endwise reciprocatory movements t0 said needle-bar includes a needle-bar driving stud operatively connected to said rotary arm shaft.

6. A sewing machine as set forth in claim 5 including means for locking said driving stud to said needle-bar so that said needle-bar may be driven by said rotary arm shaft in endwise reciprocation and wherein said means lfor interrupting the endwise reciprocation of said needlebar includes means for disengaging said driving stud from rocking engagement with said needle-bar at predetermined intervals dependent upon the contour of a cam selected to be engaged by a cam follower, said last named means including said activating arm.

7. A sewing machine asset forth in claim 1 wherein said one vcam means -includes a cam having a contoured surface, cam follower means for responding to the contoured surface, an arm operatively connected to said needle-bar and said cam follower means, said arm being actuated when said cam follower means responds to said contour surface, means operatively connecting said arm and said needle-bar, the actuation of said arm being capable of simultaneously jogging said needle-bar and causing the actuation of said means for interrupting the endwise reciprocation of said needle-bar.

8. A sewing machine as set forth in claim 7 including means for removably mounting said cam on said cam shaft.

9. A sewing machine :as set forth in claim 1 wherein said actuating means includes a rotary arm shaft, and said means for driving said needle in endwise reciprocation includes means for operatively connecting said rotary arm shaft to said needle-bar, and said means for interrupting the endwise reciprocation of said needle-bar includes means for disconnecting said operative connection between said needle-bar and said rotary arm shaft.

10. A sewing machine as set forth in claim 9 wherein said means for disconnecting said operative connection between said needle-bar and said rotary arm shaft includes means for disconnecting said operative connection each time said needle-bar is jogged to the rst side of the center line.

11. A sewing machine as set forth in claim 10 wherein said means for disconnecting said operative connection each time said needle-bar jogs to the first side of the center line includes an activating varm connected to said means for selectively rendering said interrupting means nonresponsive to said one cam means.

12. A sewing machine as set forth in claim 11 ywherein said means for disconnecting said operative connection each time said needle-bar is jogged to the first side of the center line includes a needle-bar driving stud connected to said rotary arm shaft and selectively connected to said needle-bar and means actuated by said activating arm for disconnecting said driving stud from said needle-bar.

13. A sewing machine as set forth in claim 12 wherein said means for disconnecting said ydriving stud includes a locking lever connected to said driving stud and adapted selectively to lock said driving stud to said needle-bar.

14. A sewing `machine as set forth in claim 13 wherein said driving stud is slidable on said needle-bar and said needle-bar is formed with a slot intermediate the needlebar ends, and means for biasing said locking lever into engagement with said needle-bar slot thereby locking said driving stud to said needle-bar.

15. A sewing machine as set forth in claim 14 wherein said locking lever is mounted at one end for pivotal movement toward and away from said needle-bar and said activating arm is mounted for pivotal movement toward and away from the free end of said locking lever whereby upon activation of said operator influenced means into the skip-stitch mode said activating arm is moved toward said locking lever, said locking lever being brought into contact with said activating arm as said needle-bar is jogged to the rst side of the center line thereby pivoting said locking lever outwardly away froml said needlebar against the action of said bias means to free the driving stud from locking engagement with said needle-bar.

16. A sewing machine as set forth in claim 15 including means for holding said needle-bar in a raised position after said driving stud is disconnected from locking engagement with the needle-bar.

17. A sewing machine as set forth in claim' 15 wherein said activating arm is canted at an acute angle from the vertical and in a direction toward said locking lever, the operative relationship between said locking lever and said canted activating arm being such that said driving stud is always disengaged from the needle-bar near the top of the vertical stroke of -said needle-bar.

18. A sewing machine as set forth in claim 15 including means for preventing rotation of said needle-bar as the needle-bar is driven in endwise and jogging movements.

References Cited UNITED STATES PATENTS 2,318,200 5/1943 Cobble et al 112-221 X 2,333,689 11/1943 Sigoda 112f-221 X 2,346,467 4/1944 Bills et al 112.-221 X RICHARD T. SCANLON, I R., Primary Examiner.

U.S. C1. X.R. 112-22l. 

